著者

石井 卓郎 Ishii Takuro

出版者

名古屋大学農学国際教育協力研究センター

雑誌

農学国際協力 (ISSN:13475096)

巻号頁・発行日

vol.8, pp.89-121, 2010-02

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わが国における陸稲育種研究は,食糧自給率の向上を目的として1929年に農林省が全国の五ヵ所(秋田,茨城,三重,鳥取,鹿児島)に陸稲育種指定試験地を設置したことに始まる。戦後の組織再編以降は,茨城県農業総合センターが唯一の指定試験地として品種育成を担ってきたが,作付面積の減少等の理由から2005年度で終了した。この77年の間に61品種が育成されている。この間の研究内容および成果は時代背景ごとに大きく分けると以下のとおりである。 1929-1950 食糧の増産が強く求められた時期である。とくに開拓地では,陸稲は経営が安定するまでの欠かせない食糧として重視された。品種育成は,耐干性の向上と多収性を目標として推進され,この結果,短強稈で栽培しやすく,当時としては良食味の「農林12号」や多収品種「農林糯26号」等が育成された。また,播種期や栽植密度,敷わら効果等の陸稲栽培に関する基本的な研究やカリ欠乏土壌やリン酸欠乏土壌等の開拓地で栽培するための品種比較試験が行われた。 1951-1970 引き続き食糧の増産が求められる中で,畑地かんがい設備が整備され始めた。水稲品種ではいもち病の多発等のため,畑かん栽培への転用が困難なことから,畑地かんがいを前提とした専用品種の育成が目標とされ,主に水稲と陸稲との交配により品種育成が進められた。この結果,強梓・多収品種「オカミノリ」(農林24号×水稲農林29号),良質・多収品種「ミズハタモチ」(越路早生×ハタコガネモチ)等が育成された。また,かん水栽培法や陸稲の麦間栽培法に関する研究が多くなされた。 1971-1988 米の生産調整が開始される中で,陸稲は野菜の連作障害を緩和する効果があることから,クリーニングクロツプとして野菜作の輪作体系に取り入れられ始めた。このため,野菜作との組合せが容易で干ばつ回避効果も期待される早生品種の育成が主目標とされ,早生熟期「トヨハタモチ」や「キヨハタモチ」が育成された。また,陸稲により連作障害が緩和される仕組みに関する研究や外国陸稲の耐干性(深根性)の評価と交配母本としての利用,ハウスを利用した独自の耐干性検定方法の開発が進められた。 1989-2005 野菜作を中心とする畑作経営が一段と集約化する中で,野菜作との組合せがより容易な極早生熟期で,安定生産が可能となる高度耐干性品種の育成を目標として品種育成が推進された。この結果,まず,外国陸稲「JC81」に由来する深根性を導入した中生・高度耐干性品種「ゆめのはたもち」が育成され,次に「ゆめのはたもち」の耐干性と「関東糯166号」の早生・耐冷性を集積することに成功した早生・安定多収品種「ひたちはたもち」が育成された。また,陸稲需要の拡大を図るための加工特性に関する研究やイネゲノム研究の進展にあわせて陸稲を遺伝資源として利用し,陸稲の有する新規いもち病圃場抵抗性遺伝子を水稲へ導入する研究が進められた。本発表では、主として演者らがこれまでに行ってきた研究成果をたどりながら、土壌環境の中で、とくに、土壌水分を中心にその作物根の発育や機能に及ぼす影響を、可塑性をキーワードに考えてみたい。 In 1929, the government breeding program began upland rice breeding research at five breeding stations (Akita, Ibaraki, Mie, Tottori and Kagoshima). Though only Ibaraki Agricultural Center continued upland rice breeding after the post war reorganization, upland rice breeding ended in March 2006 because of a sharp decrease in cultivation area. Sixty-one varieties were bred from 1929 to 2006. Many studies had been carried out on drought resistance and other similar conditions. The achievements of upland rice breeding in each time period are as follows: 1929-1950 The increase of crop production was strongly requested. Upland rice played an important role until farming managements stabilized particularly at reclaimed field. The breeding objectives in this period were mainly high yielding and drought resistance. As a result “Norin 12” which is a high yielding variety with relative short culm and “Norinmochi 26” which is a high yielding glutinous variety and others were released. There were also discussions on basic cultivation studies such as sowing time, sowing quantity and straw mulch effect as well as a variety of screening tests for reclaimed fields suffering from potassium and/or phosphorus deficiency. 1951-1970 The field irrigation systems began to be equipped in upland field, while the increase of crop production was still requested. As the paddy rice was not suitable for upland cultivation due to damage from blast disease, the specific varieties were requested for the cultivation at upland fields with irrigation systems. Therefore breeding was mainly promoted by a cross between paddy rice and upland rice. As a result high yielding varieties such as “Okaminori”, “Mizuhatamochi” and others were released. Additionally many studies on the cultivation methods using field irrigation and cropping systems with wheat or barley cultivation were carried out. 1971-1988 When the overproduction of paddy rice became a serious issue, upland rice began to be used as a rotation crop because it had an effect on the decrease in continuous cropping injury of vegetables. Thus, the breeding of early maturing varieties which made the rotation with vegetable cultivation efficient and were expected to have the effect on drought escape was promoted. As a result early maturing varieties such as “Toyohatamochi” and “Kiyohatamochi” were released and evaluations of deep rooting of foreign upland rice cultivars as well as their utilization as breeding materials were conducted. The greenhouse method for evaluation of drought resistance was also originally exploited. 1989-2005 As vegetable cultivation became more intensive, the very early maturing varieties with high drought resistance were requested for the stable management of crop rotation. As a result, first medium maturing variety “Yumenohatamochi” with deep rooting which was derived from foreign upland cultivar “JC81” was released. Then a very early maturing and stably high yielding variety “Hitachihatamochi” which had the drought resistance acquired from “Yumenohatamochi” and very early maturation and cold tolerance acquired from “Kantomochi 166” was released. Additionally, studies on the processing suitability for the promotion of upland rice consumption were discussed. Based on the idea of using upland rice as a genetic resource, the introgression of blast resistance genes from upland rice into several types of paddy rice by using DNA markers was also promoted.

著者

石井 卓郎 Ishii Takuro

出版者

名古屋大学農学国際教育協力研究センター

雑誌

農学国際協力 (ISSN:13475096)

巻号頁・発行日

vol.8, pp.89-121, 2010-02 (Released:2013-03-05)

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The proceedings included herein are the papers presented in the Seventh ICCAE Open Forum held in October 20th, 2006 at Nagoya University, Japan.